Tensai
by Shadewolf7
Summary: Tensai: 1) Genius, protégé. 2) Natural disaster. Accounting for the fact that Ichigo's lack-of-trying in school STILL has him in the top 50, despite all the supernatural disturbances that cut into his life - what if he hadn't taken Rukia's powers that day, and instead only awoke his own? (No more romance than Canon, so don't ask.)
1. Prelude

_So, yeah: Characters and settings? Not Mine. For the record._

_**Prelude**_

Intelligence is rated by the ability to take in, understand, and _use_ new knowledge. Kurosaki Ichigo was a genius. _Tensai_, even, and he knew it. When applying the term to himself, he always visualized the Romanji* spelling, as it gave no direct correlation to meaning—he was fully aware that his abilities inside the classroom were _far_ from the only abilities he had. Seeing ghosts was obviously unusual, and being able to interact with them on a physical level was something he had not seen another person in town do.

The evening before a random street-thug he had very deliberately not gotten the name of had skateboarded _through_ the spirit of a young girl. He'd flattened that one and his gang in retaliation for the girl's tears.

And he was well aware his strength wasn't entirely physical. He knew karate and jujitsu, as well as a smattering of other martial disciplines in a basic sense, but he hadn't had formal training in over three years and he didn't make a habit of strength-building exercises outside of the occasional gym-class weight-training session. He wasn't on the track team and didn't spend much time running cross-country on his own. Still, he was capable of running from his house to the high school in under three minutes without even getting winded. He could punch a hole through a foot-thick concrete wall without even bruising his knuckles.

None of that was physically _possible_ without intensive training.

And _tensai_ could mean 'natural disaster' as well.

He was aware of the power within himself, aware enough to be able to use it to increase his physical abilities, but he was hesitant to try manifesting that power _outside_ of his body. The last time he'd done so—just a little, out the palm of his hand—he'd blasted a tree in half at the park on the edge of town.

A _tree._ Not a small one, either, and the natural give of wood would theoretically mean it would have been easier to blast a concrete post apart from that kind of concussive force. Which, just to top off the idea of 'not applying laws of physics' hadn't even had any kind of recoil.

While the power was interesting, it was also something he was uncertain how to regulate or manipulate and a city in Japan didn't seem like a good place to experiment with it.

The monster and the woman earlier… both had felt of power like-and-unlike his own and each others'. There had been some fundamental similarities, and there was a 'Ishida Uryuu' in his class that had another similar-feeling power (different from the spirits), though all of them possessed comparatively less than his own.

He tended to try to keep attention off himself, keeping his power reigned in and held quiet, not deliberately drawing attention in school. Freshmen year had only just begun and he was already bored near out of his _mind._ Classes were a joke; he didn't bother paying serious attention, though he kept half an ear on the lectures just in case the teachers ever came up with something not in the reading material that he didn't already know.

Hadn't happened yet, but hope springs eternal.

He sighed, turning his thoughts back to the black-clad samurai woman and the monster from town.

Something… well. He had been aware of the existence of both the black-clad samurai and the monsters, though he was fairly sure the last samurai in the area had been both male and somewhat less powerful than the woman.

They were spirits of some sort, _obviously_, but he stayed out of their way and they ignored him. The monsters didn't pay him any attention so long as he kept his power hidden and the samurai didn't take any notice of him either.

But that didn't mean he didn't _wonder._ He kept track of where the more powerful spirit-entities in his town were, just in case, but he wasn't sure what to do about them. There was the option of confronting one of the samurai, but he'd gotten the impression that the last one would have pulled a sword on him as soon as look at him if he'd shown any indication of _seeing_.

The new one, though… well. He'd watch her for a few days before deciding.

Issue settled, Ichigo closed his eyes, fully intending to get some sleep.

That, of course, was right when Murphy decided to strike. The energy in his bedroom wall shifted into a pattern he didn't recognize, fueled by a power that was only vaguely familiar.

The female samurai stepped through his wall behind a black butterfly, foot tapping lightly against his desk before she dropped to the floor, one hand on the hilt of her blade.

"It's near," she murmured to herself, clearly dismissing Ichigo's presence entirely.

Of course, he _was_ keeping his power tightly restrained—more habit than anything else, by this point—and she probably didn't realize he could see her.

But if by 'it' she meant another of those monsters…

"How near?" Ichigo demanded, surging to his feet. Because even the smallest of the monsters he'd seen so far would be able to cause significant damage to the house… and the people inside.

The samurai startled as he flicked on his desk-lamp and pinned her with a focused glare.

"You… you can see me?"

"Not the time to wonder about that," Ichigo snapped, "I can't track that monster right now—if you're sure it's near, then it's hiding itself, and I may be able to _see_ those things but I don't have a very effective way to _fight._"

"Hiding itself?" her voice took on a tinge of alarm, "A normal Hollow shouldn't be _able_ to hide itself!" But that _would_ explain why she didn't have an exact location. "It must be powerful…"

Something impacted the house and Ichigo heard his sisters scream.

_xxxx_

The next two minutes passed in a blur—too long and too short all at once. Karin and Yuzu had been grabbed in one oversized hand, but the samurai slashed the thing's arm and it's grip faltered. Ichigo managed to catch Yuzu—the more injured of the two—and Karin twisted in the air to land mostly upright.

He herded the dark-haired twin deeper into the house while carrying Yuzu and left both of them under his father's care, the older man squinting out the hole in the kitchen wall like he was trying to see but couldn't.

"What _was_ that?" Karin demanded, "I can't—it's like a blur in the air—"

"Hollow," Isshin breathed, so low that Ichigo barely caught it. He didn't have time to wonder about his dad's apparent knowledge, though, because the samurai was batted aside by the fish-faced creature's arm, impacting the light-pole nearby with enough force to dent it.

"Kuso!" he snapped, darting back outside. He ignored Karin's sharp cry and skidded to a halt in front of the dazed woman, the creature reeling back from a wound on its neck.

"Oi, are you all right? Oi!"

The woman opened her eyes with clear effort, rolling herself semi-upright against the base of the post, sword clicking as it tapped against concrete. "Do you… want to save your family?"

"Of course!"

"I can… give you my power. Thrust my sword… into your heart… and I'll pour my power into you."

Ichigo met an amethyst gaze, and took hold of the blade without hesitation.

The instant the woman's power flooded the blade in his heart, the pain became inconsequential. Something inside him latched onto the pattern of power and _shifted_, and for a moment—just a moment—pain became silencing _agony._

He didn't need her power. He had his own_._ Something inside—split, rearranged—_changed_—and there was a blade in his hand and another through his heart. The one in his chest flickered for less than a heartbeat—

—and his body fell one way while _he_ moved the other, the blade in his hand a mere extension of his will and the monster crashed into the concrete barrier beside the road hard enough to crack it, dissolving, head split in two.

He took a moment to examine the katana in his hand that didn't feel like any weapon he'd ever held. The blade itself was dark silver, several shades darker than steel, the hilt red-wrapped with a short blue tassel like the one on the hilt of the samurai's blade.

He could feel wood-and-leather at his hip and his hand moved without thought, sheathing the blade without difficulty despite the fact he'd never handled a live-blade sword before.

The dust began to settle.

Karin screamed, Ichigo's name lost in terrified volume, and he could hear his father ordering her to remain with her unconscious sister, voice tense and hard, a tone Ichigo had never heard from his father outside medical emergencies, then the older male was running across the street to—

_Oh._ Ichigo swallowed, recognizing his own body crumpled on the ground, mere feet from where the visibly stunned samurai-woman was trying to stand. There was a fair amount of blood, but he couldn't tell by sight if any was his own.

It was clear that Isshin couldn't see spirits themselves. Would he be able to see the blood of a spirit? No, Ichigo realized, or the man would be more aware of the spirit next to him.

Ichigo watched silently as his father's shaking hand checked his body for a pulse, saw Isshin's face pale and his eyes slide closed, his expression crumpling into something agonized as he dragged his son's body into his arms.

Isshin knew _something_ of what was going on, had recognized the creature even while having been unable to see it… but that didn't matter, _couldn't_ matter as Ichigo watched his father's ever-ludicrously-cheerful composure crumble away like so much wet sand.

Ichigo glanced at the samurai as she dragged herself upright and he hesitated for only a moment before stepping between her and his father, "Hold on a minute," he said quietly. He'd been willing to die if that's what it took to protect his family, but seeing his father kneeling there, fighting tears…

He reached forward, intending to place a hand on Isshin's shoulder, his arm brushing his own body's head.

Flesh sucked him in like a whirlpool.

Ichigo found himself gasping in air in his father's arms, jerking once before going limp again, shaking at the effect of inhabiting a body whose heart had lain still for over two minutes.

Arms tightened around him and he felt more than heard the relieved sob tear through his father's chest.

"Oyaji, let me up," he pushed weakly at his father's chest, body protesting even that much movement. "She's hurt."

There would be time to talk later.

_Xxxx_

_Romanji: Latin alphabet phonetic spelling of Japanese words. Thus, the kind most English-speakers are familiar with and able to read, if not understand._


	2. Chapter 1

_Because the facts that I am a doctor's daughter and Ukitake Juushiro has a chronic illness combine to equal 'me wanting to fix him', anime character or not. You'd think Ichigo (as a doctor's son) would catch on in canon._

_**Chapter 1**_

Ichigo was, of course, the only one in his family capable of seeing—and therefore _treating_—the samurai. He knew she wasn't _really_ a samurai, (lack of daisho* a pretty big giveaway, no matter the fact that she was a _spirit_) but without anything else to think of her as and no real time for questions, it worked well enough as a descriptor.

He sighed, settling her in a patient's room in the clinic-side of the building while his dad hovered anxiously, then turned with the intent of gathering basic first aid materials—he didn't really know what would work on a spirit, after all.

"Wait here," he told the still-silent woman, "I'll be back in a few minutes. Try not to move around too much—that may not be too deep, but it's pretty wide and I'd rather you didn't restart the bleeding."

Isshin was following him, somber and silent, and that was… kinda creepy, actually.

"Son…"

Ichigo paused, glancing back down the hall to see that his old man had closed the door to the patient room he'd left the injured woman in.

"What happened?"

Ichigo sighed and gave a brief summery as he made his way towards where the medical supplies were kept.

"Not that way," Isshin laid a hand on his shoulder, stopping him. "I-I'd _hoped_ you wouldn't find out about this until… I just wanted you and your sisters to have normal, _human_ lives. But… I owe you an explanation. How badly is the Shinigami girl hurt?"

_Shinigami._ A name for the type of spirit at last. "Badly enough that it needs to be seen to, but it shouldn't be life-threatening. Although she hit that lamppost pretty hard, so she might have a concussion. It would have killed a human."

"Spirits with power are much more resilient than humans, son. I don't regret what I did for your mother, for _our_ family… but now I wish that the recovery was faster. I can't even _see_ right now; haven't been able to since before you were born. It means Hollows don't hunt me and Shinigami don't notice, but… You were born with power. And power… _attracts_ Hollows."

Isshin sighed, shaking his head, "Still, time for proper explanations later. Now—here."

Isshin opened the door to his own bedroom, slid open the closet, and pulled out a large first-aid kit. "You need bandages made from reishi or imbued with reiyōku* to treat wounds to a spirit. I can't see what's in here anymore, but none of it would have needed to be replaced like human-world items. And… lets just say the afterlife doesn't worry about infections for a reason. Besides, human-world bacteria wouldn't be a problem to Shinigami anyway."

Ichigo nodded, taking the kit. He had a lot to think about.

"Get the basic explanation from the Shinigami girl. I don't want to tell you too much before then, or she'll get suspicious. Right now, I can't afford too much scrutiny."

"Right," Ichigo sighed, glanced at his father. "Well. Get some rest, Oyaji. We can talk tomorrow after school, if you want."

Isshin nodded and Ichigo hesitated with a hand on the doorframe, glancing back. "… You don't have to tell me everything."

Isshin blinked as his son disappeared from his line of sight, huffing a half-laugh. He'd known Ichigo longer than anyone else had, but his son could still surprise him.

_xxxx_

"... What's your name?" Ichigo asked as he finished securing the bandages around the small Shinigami's torso and tugged black cloth back up to cover them.

"Kuchiki Rukia, Shinigami," she answered after a moment.

"Kurosaki Ichigo," Ichigo let his lips twitch into a wry smile, "high school student."

"… You rejected my power," Rukia murmured, wondering and soft. "That… should have killed us both."

Ichigo shook his head, "Not rejected," he stated, taking a single step back from the bed and tugging out the visitor's chair to sit. "_Returned._ I… didn't need your power. I have my own. I just hadn't figured out how to _use _it. You woke it up; that's all I needed."

"You're _Shinketsu?_ A true-born in the Living World? That hasn't happened for _centuries._"

"I wouldn't know," Ichigo shrugged, rubbing a hand over his face. "I've done what I can, but I don't really know anything about healing spirits. Is there someone anywhere nearby who can help you?"

"I can call for a medic from Fourth," Rukia reached into the black shihakusho she was wearing and pulled out what looked like a standard flip-open cell phone. "I'll need to explain you to them, but Shinketsu are… well. You'll be drawn in to some degree whether you want to be or not, especially with all the Hollows in this town. And, since you don't have any of _my_ power, they won't be able to say anything against you."

"You offered me your power to _save lives_…" Ichigo said slowly, "… and that's _illegal?_"

Rukia nodded, face grave. "Even the attempt could get me a few years in prison," she admitted. "If you'd actually _taken_ my power and it had been found out…"

"Let's skip that part in your 'explanation', huh? Just say the Hollow knocked me out of my body, or something. I've certainly heard of out-of-body experiences from near-death often enough."

After a moment, Rukia nodded. "That might be for the best. All right, I'll contact Ukitake-taicho and let him know what's happened. He'll contact the Fourth Division and send a medic. You should probably get looked at, too—even though you're Shinketsu, it _had_ to be hard on your body to be without a soul for so long."

"Fair enough," Ichigo rolled his shoulders, wincing. "I _am_ feeling a bit off. I'll be back in a couple minutes—I need to check on my sisters."

_xxxx_

Ichigo _did_ check on his sisters, both of whom were sleeping peacefully—probably something his Dad had given them, considering—and slipped further down the hall to knock lightly at his dad's door.

The instant reply was unsurprising.

Ichigo stepped inside, closing the door behind him. "Her name is Kuchiki Rukia—" he cut himself off at the visible wince. "Bad?"

"I don't personally know a 'Rukia', but the Kuchiki are a noble family. One of the Great Houses; someone will be looking for her. If she gave you her power…"

"She didn't," Ichigo cut in, wanting to settle that quickly, "Not that she didn't _try,_ but… something _woke_ inside me and I just… pushed _her_ power back into her blade. She called me 'Shinketsu' and she's calling a captain for a medic. I just thought you should know in case you need to lie low for a while, or something."

"Ah," Isshin visibly thought about that. "That's… probably a good thing. I don't have any power right now, so even if it's someone who knew me, I won't _feel_ the same to them. That's more important than _look._ And… I'm not the same person anymore. They'll probably think that you got your reiatsu from your mother—you even may have, she had a lot for a human—but I'll stay in here tonight. If they're still around in the morning… well, we'll figure it out. I have a friend who could probably do something to keep them from noticing, even after my power returns. It's… starting to. I could _almost_ see that Plus spirit that was following you earlier. It takes more power to see Shinigami and Hollows."

Ichigo blinked at him, "Well, see you in the morning, then. Rukia said that she wanted the medic to take a look at me, too—something about it being hard on a human body to be without a soul. I'm kinda feeling that."

Isshin made a sound that was only half laugh, "Yeah. That's a good idea. Whenever you're not in your body—it's physically dead*_,_ unless you have a imitation-soul to keep things like, you know, _heartbeat_ and _breathing_ going. I thought… I couldn't see you, and I thought you were _dead_."

Ichigo winced, "Sorry about that-"

The doorbell rang.

"We'll talk tomorrow. It sounds like the medics are here."

_xxxx_

Ichigo opened the door to two people wearing white haori over black shihakusho, both wearing single blades sheathed on their left hips. He gave a mental shrug; Rukia wouldn't let her blade be out of easy reach, so it made sense that the others wouldn't either. Considering the way his own blade felt… and he could still feel it, human body or no… yeah. He could empathize with that.

They felt much more powerful than Rukia—when it came to terms of raw reiatsu, still less than what he knew he possessed, but far more refined than his own firm suppression. Something within shifted, a flicker of interest not entirely his own, a shadow of the blade hidden with his soul.

Man and woman, he catalogued absently. The man had white hair a little longer than shoulder-length and a kindly intrigued expression. The woman had long black hair, pulled around both sides of her throat and braided down the front of her shihakusho. Strange style, but it _would_ keep long hair out of the way.

No time to worry on that, not yet. "I take it you're the ones Rukia called?"

Twin blinks, then the man smiled. "Yes, I'm Ukitake Juushiro, Captain of the Thirteenth Division; and this is Unohana Retsu, Captain of the Fourth. Are you Kurosaki Ichigo?"

Ichigo nodded, stepping to the side, "Come in. Rukia's in one of the clinic's overnight single rooms. My family knows I can see spirits, and Dad didn't really want to find out what would happen if someone walked in to see a blanket hanging in the air." He paused, "Granted, we don't usually keep patients overnight, the hospital's better equipped for that, but night-time emergencies happen, and better to be careful."

He closed and locked the front door, "This way."

_xxxx_

Rukia started to jerk herself upright the moment Ichigo stepped through the door, giving her a look at the white-haired captain behind him.

Ichigo crossed the room and pushed her back with a hand on her good shoulder even as she winced sharply, reaching to press against the bandages covering her wound even as she stuttered out, "U-Ukitake-taicho!"

A quick glance showed spots of blood soaking through white cloth and Ichigo huffed irritably, "What did I tell you about _moving?_ You're bleeding again, idiot," he glanced back at the door, "Oi, Unohana-san? You're a—healer, right? She could use one."

"Unohana-taicho, too?" Rukia blinked in shock, "Why would…?"

Ukitake smiled at her even as he made sure to stay out of the other captain's way, "The entire situation is… a bit unusual. We decided it was best if Retsu-san checked over Kurosaki-kun herself, as none of the others have had to deal with prolonged soul-separation in a human. I think Isane-san is the only other with any experience and she was only called for a situation lasting under forty seconds, and that was with the Chain of Fate still attached."

Chain of Fate? Probably the chains he saw on normal spirits' chests, always broken. So… attached meant alive? The comment implied that his _wasn't_, but the fact they were calling it 'separation' instead of 'death' meant something. What did that make him?

"Oh," Rukia sighed in relief as the Fourth Captain let the green glow around her hand die out and stepped back.

"That should do it, Kuchiki-san. Still, try to get a good night's rest."

"Hai, Unohana-taicho."

Ukitake smiled, "It's good to see that you're all right. When the Twelfth announced a Hollow with level six reiatsu in Karakura... well, I was concerned for you. Your request for medical aid did not precisely soothe my worries."

Rukia flushed, glancing aside, then blinked and looked back at the white-haired captain. "Level _six?_ That's mid-lieutenant level!"

"You should see about upgrading the trackers you guys use," Ichigo observed, setting aside the dead/alive question for later. "I'm going to assume you guys are mostly ranked by power and skill, right? And reiatsu would be 'power', so… skill notwithstanding, that thing felt maybe half again as powerful as Rukia. And it was fast. So… if those trackers gave you guys information on power level, you'd know when to call backup, right? It would probably save you guys a lot of trouble, if not lives."

"That is… a very good point, Kurosaki-san," Unohana murmured, eyeing the human before her with interest. "I will talk it over with Mayuri-taicho… although he likely would not care about _lives_, he may take it as a challenge to his professional pride if I word it correctly."

"That aside," Ukitake spoke up, giving Ichigo the same sort of pleasantly intrigued look that Unohana sported, "We should let Rukia-san rest as well as make sure you took no lasting damage from your foray outside your body, Kurosaki-kun."

"Aa," Ichigo moved toward the door, "Sleep well, Rukia," he offered before turning his attention to the two captains, "My room's this way. My little sisters are sleeping, but they probably won't wake up. I think Oyaji gave them something—the Hollow grabbed them, and they were pretty shaken up. Actually… Unohana-san? Could you look them over? Yuzu was unconscious for a while, and human medicine doesn't really have a way to treat mild concussions."

"Sisters?" Ukitake asked even as Unohana nodded with a firm affirmative.

"Yeah," Ichigo tapped once on the twins' door before pushing it open to let Unohana inside, "Karin and Yuzu. They're fraternal twins. Yuzu took over most of the housework since Kaa-san died. Dad's a total spaz; he would never be able to take care of the house _and_ keep clinic records in order… actually, I take that back. Yuzu files most of the paperwork, too. Oyaji's pretty much the _least_ organized person I know. Karin helps out wherever she can."

"Oh? Could we speak with your father?"

"No; he can't see or hear spirits at all. Yuzu can sometimes hear the spirits I usually see around town and Karin can see them, but neither one of them saw that Hollow or Rukia. I'm pretty sure there'd be no point in you trying to talk to Dad."

Ukitake hummed consideringly.

"… Although…" Ichigo hesitated, "Oyaji _did_ say Kaa-san could see ghosts. And… when I was little, I couldn't tell the difference between spirits and people. I would talk to spirits pretty often, and sometimes Kaa-san joined in."

"Then you probably got your high spirit energy from your mother, Kurosaki-san," Unohana stated, emerging from the twins' room. "Both of them will be fine," she added at his questioning glance. "I still need to take a look at you, though, and your hands seem to be trembling."

"Yeah," Ichigo led his way to his room—spartan and neat, as always—and dropped down to sit on his bed. "I've been feeling off ever since I got back in my body, but that's not really a surprise. Normally, it takes _days_ for a human body to sort itself back out after a prolonged period of clinical death. And my heart did stop—Dad was _terrified_ for a minute there."

He got a frown from the healer-captain for that, but he waved his hand dismissively, "My sisters and Rukia were the ones who'd actually been _hurt._ I just suffered temporary cardiac arrest. Given the circumstances, even without treatment I should be fine. Treatment will just speed up recovery. Give me _some_ credit, Unohana-san, I live in a _medical clinic._"

Unohana blinked and Ukitake gave a chuckle that devolved into painful-sounding coughing.

The healer turned, visibly concerned, and Ukitake waved at her as he caught his breath, "I'm all right. Check over Kurosaki-kun first."

Ichigo re-ran that short interaction several times, his habitual frown deepening. "Ukitake-san, does that happen often?"

"Hai," the white-haired man smiled, a bit ruefully, "I've had it for most of my life."

"… Do you ever cough blood?"

Unohana didn't hesitate in moving her green-glowing hands over his torso (which was making Ichigo feel a _lot_ better, if he were honest) but her eyes sharpened as she answered for the other Shinigami. "Yes, he does."

"Fever? Loss of appetite while suffering from fevers?"

This time, the healer's hands did pause as Ukitake answered cautiously, "Yes to both."

"Any other common symptoms?"

Ukitake shook his head, "Not really, no. Occasional organ damage, but not ever as bad as my lungs."

Ichigo made a noncommittal hum, thinking. Bacterial, probably, but not bacterial pneumonia…

"Are those… recognized symptoms in the Living World, Kurosaki-san?" Unohana asked carefully, returning to her work.

"Yeah, actually. Long term illness and not _dead_ yet… Hm. How does your healing work?"

"Why do you ask?" Ukitake questioned, noting Unohana's darkening expression and doing his best to avert any blatant disapproval from one of the most terrifying people _ever._

"Because it might help me narrow things down. They are pretty widespread symptoms, after all."

With that, the shadow left Unohana's expression, "Simply put, we manipulate reishi in order to convince the body to heal itself from damage."

"Damage… what of illness?"

"There are very few illnesses in Soul Society, Kurosaki-san," Unohana informed. "Most pass quickly when the effects are treated."

Ichigo nodded slowly, "Probably Tuberculosis, then. There aren't a lot of illnesses in the Living World that can't be fought off naturally, given enough time and some way to keep symptoms under control, but there are a few that just… _spread._ Tuberculosis is one of those—it's a bacterial disease, usually starts in the lungs. Left untreated, it will eventually spread to other organs, if accumulated damage to the lungs doesn't just kill. Sooner or later, scar tissue adds up to suffocation in humans."

"What is this… 'bacterial disease'?"

Ichigo stared for a long moment as Unohana let the green glow peter out before stepping back. "You don't know—all right. Um, they're—uh, hm. How do I explain this? They're… tiny creatures. They're _everywhere_ in the Living World. Most are fairly innocuous, neither helpful nor harmful. Some are helpful—there are quite a few that human bodies actually can't live without. A fair number are harmful—some few are _very_ harmful. Tuberculosis is caused by one of those few. They invade the body, usually through the lungs, and start to feed on them, causing lacerations. Let alone, they multiply and spread and sooner or later start to cause damage to other organs.

"If you have a way to repair damage without leaving scar tissue, it could continue for a long time. The body would naturally try to fight off the infection, but after a while the bacteria would become resistant to natural antibodies and start to spread faster. If you're only treating the _effects_ and not the _disease…_ Well. Sooner or later, it'll turn fatal."

"Do you have a way to cure it?" Unohana's voice was intent, eyes almost desperately pleading.

"Yeah. We have a wide range of antibiotics that'll take out bacteria, but you should probably have it tested first. Each strain needs to be handled differently, and the wrong antibiotic could even make things _worse._ And I'm not even sure it would work on a spirit—"

"We have false bodies we can use to interact with humans. Do you think…?"

"False… bodies? If the bacteria were forced into a physical body… that might work. Otherwise… huh. Antibiotics are basically poisons that effect bacteria but not humans, and if I tried flooding one of the normal treatments with reiyōku, it might make it work either way. Um… I'd need a blood sample to test that, though. If you get yourself a false body and get me a blood sample from your normal form, I can talk to my dad about picking up the right kind of antibiotics. It'll take a few days—the hospital likes paperwork—but the sooner you get back, the sooner we can get started."

Unohana stepped forward and wrapped Ichigo in a tight hug, much to the human's consternation. "Thank you."

"I still don't know if it'll work," Ichigo cautioned as the woman drew back.

"No, but… it's a new direction. If this _doesn't_ work, we can set the Twelfth on it. Either way… it's the best news we've had in years."

Ichigo glanced at the stunned-to-silence Ukitake and dipped his head, "You're welcome, then."

_xxxx_

"I was going to explain—as Shinketsu, you will need to know, regardless of your current state as a living human."

Ichigo waved him off, "Rukia's assigned to Karakura for now, I can ask her if anything immediate comes up. You're coming back soon, anyway, right? It can wait a while."

Ukitake smiled, small and genuine. "Very well. And… thank you."

Rice-paper doors slid shut and faded.

Ichigo made his way back inside, collapsing into bed for what little sleep he'd be able to manage before morning.

_xxxx_

_Daisho: Paired swords. Katana and wakizashi together were worn by samurai only partly for actual use. They were also used as a badge of office; the mark of the feudal Japanese equivalent of European knights. Both had to be both nobility and warriors._

_Reishi: Spirit particles_

_Reiyōku: Spirit energy/power_

_physically dead: I'm not sure it's ever directly addressed in Canon, but the implication is that a normal soul's Chain of Fate indicates whether the body is alive or dead while in the Living World. A broken Chain means 'dead', obviously, while one still attached to the body means 'alive'. Shinigami, by definition, are _not_ normal souls and do _not_ possess Chains of Fate. Gigai, being false bodies and never alive to begin with, are completely dormant without some kind of driving force, whether Shinigami or Gikon. (Or Mod-Soul, as the case may be.)_

_Missing the Chain that should have been binding it to its soul, my belief is that Ichigo's body would also completely shut down without him inside it. And when the heart stops beating, bodies undergo quite a few detrimental changes that—even if the person is revived—usually have at least short-term consequences. (Can you tell my dad was a doctor? He's retired, but the things you learn from the guy who used to do the autopsies is… kinda morbidly interesting, if I'm honest.) Obviously, none of that is addressed in Cannon, but this is where my thought-train goes._


	3. Chapter 2

_Following my initial breakdown of Ichigo's situation; this is the most likely result, regardless of Unohana Retsu's interference. There has to be _some _drawback to being human, after all, and when not familiar with living bodies... well. There's a reason medical school lasts so long._

_**Chapter 2**_

When his alarm went off, Ichigo took several seconds to register the sound before making an attempt to stop it, struggling upright against his blankets to swat at the snooze button before sliding the alarm switch to 'off'.

Abruptly, the previous night's events registered and he staggered to his feet, stumbling down the stairs in his haste to check over his sisters. Unohana had healed them, but that didn't mean much for emotional state.

"Karin, Yuzu, are you two all right?"

"Last night… it was strange. It feels like a bad dream," Yuzu set a plate on the table, "But…" she looked out the side of the house, where there had been a wall and window at one point.

"Yeah, there were spirits here. One of them healed you two. Also… there's one in the clinic. I should go get her and remake the bed, in case someone needs that room later." Ichigo blinked slowly, his vision fuzzing around the edges.

"Onii-chan… are you all right?"

"Yeah," he ran a mental check of himself. He wasn't feeling _bad,_ really, "Just… really tired."

He turned toward the clinic, calling over his shoulder, "Oi, Yuzu—could you make a spare plate? I don't know if she can eat human food, but…"

"Mm," Yuzu nodded, smiling. "We can't be bad enough hosts to not offer!"

Ichigo hid a faint smile. Even if she couldn't see her guest, Yuzu _loved_ having people to take care of. It had apparently been the perfect way to cheer her up… and when Yuzu was pleased, Karin was pleased.

_xxxx_

"Oi, Rukia," Ichigo tapped the door firmly.

A moment later, said door swung open, revealing a somewhat ruffled-looking Shinigami. "Oh, good morning, Ichigo."

Ichigo ignored her somewhat subdued attitude, chalking it up to either sleepiness or misplaced guilt—the latter of which he wasn't touching with a ten-foot pole without knowing the Shinigami better. "Yuzu's made breakfast; you hungry?"

"Um… aa, but… I'll need a gigai since it's human food. I ordered one earlier this week; it should be ready by now. I can go pick it up and be back in ten minutes."

Ichigo shrugged, "Sure, go ahead. Yuzu would like to meet you, anyway—she loves having people to feed. I'll let my sisters know you'll be a few minutes after I walk you to the door."

After the front door shut on what looked to the girls like empty air, Yuzu came out of the kitchen, holding a wooden spoon and visibly disappointed, "She didn't stay?"

"Eh, she said she'd be back in ten minutes or so. She can't eat human food without a fake body, but she apparently has one of those waiting for her at some Shinigami shop in town. When she gets back, you should be able to see her."

Yuzu's disappointment morphed into happiness.

_xxxx_

Ichigo smiled as he watched his sisters from his spot at the table, Yuzu cooking and Karin attempting to help and summarily being chased back from whatever mess she threatened to make. They were okay—_really_ okay. They'd been scared, but they weren't traumatized, and they were healthy and well-rested.

Which was more than he could say for himself. 'Well-rested' was something that he definitely was _not,_ although he wasn't sure why he was _this_ tired. Sure he'd only gotten about three hours of sleep, but he was a teenager and it was hardly the first time he'd stayed up late. Some aftereffect of the 'soul separation' that they couldn't fix, maybe?

Ichigo sighed, closing his eyes for a long moment only to open them when he heard one of his sisters—Karin, of course, with Yuzu still in the kitchen—stop next to him.

"Are you _sure_ you're all right, Ichi-nii?"

Ichigo offered a smile, "Yeah. Just… tired. I wish I didn't have school today; I just want to go back to bed."

"Maybe you should," Karin eyed him carefully, "Oyaji would probably call it in if you asked him. He was pretty freaked last night."

"He had reason," Ichigo muttered, rubbing a hand over his face, "but the healer looked me over. I should be fine."

The doorbell promptly interrupted and Ichigo started to pull himself up before Karin, scowling, pushed him back.

"_I'll_ get it. You said we'd be able to see her, now."

When Karin had that expression, it was best not to argue if you didn't have a _really _good reason.

_xxxx_

"Do you have a place to stay?" Ichigo asked Rukia, ignoring Isshin sulking in a corner, a metaphorical raincloud above his head.

"Ano… not yet, no. I was only supposed to be here for a few days, but the Eighth Division member who was supposed to be assigned here next was injured in a fight with a strange Hollow and he won't be out of the Fourth for another two weeks. I wasn't expecting to be here so long."

"Well, we've got enough space, I guess. You can't keep using the room in the clinic, though—we're planning on letting your captain have that one when he gets back."

"She can stay in our room, ne, Karin?"

"If Ichi-nii carries in the extra bed from the attic," Karin said dismissively. In truth, she didn't have anything against it—that Shinigami girl had fought to protect them, and fought _hard._

"Tou-san can do that," Yuzu stated firmly, turning to give their father a firm look. She didn't want Onii-chan to strain himself until he got some rest.

Isshin wandered in the appropriate direction, wailing loudly about cruel children.

Rukia _stared_, taken aback at the ridiculousness of the action.

"Ignore him," Ichigo advised, "He's a total spastic man-child."

"Just be glad none of us take after him in more than hot tempers," Karin advised.

"…" Rukia decided it was safer not to comment on the madness and went with her first question, "Ukitake-taicho's coming back?"

"Uh, yeah. He's got a pretty nasty cough, and from what your healer-division's captain explained… we might be able to cure him. I mean, I can't promise it'll work for a Shinigami, but it _sounds_ like Tuberculosis, and we have a cure for that. If it doesn't work, Unohana-san will see about finding something that will with the science division, now that she has a better idea of what might be causing it."

Rukia stood frozen, a faint tremor running through her frame. "You… have a cure? You can heal him?"

"Maybe," Ichigo corrected, "There's a chance, sure, but I don't think human medicine has been tried on Shinigami. Don't get your hopes up just yet."

A breath and she was slumping in place, something undefinable shining in amethyst eyes. "A chance… is better than anything we've had."

_xxxx_

Isshin kept a discreet eye on his son the entire morning, noting the blatant exhaustion with concern. He had sensed both Juushiro and Retsu in his home, and Retsu would not have left injuries untreated or reiatsu depleted—which meant whatever was wrong with his son was probably purely physical and on a level that Retsu didn't know how to recognize.

Damage to a body was far different from damage to a soul, and while most Shinigami who were assigned to the living world and all of the Fourth were trained in healing wounds to flesh… illness and physical exhaustion were two things they wouldn't even _recognize_ through diagnostic kido. They were trained on gigai dummies, of course, and gigai—despite looks and structure—were _not_ human bodies.

When Ichigo stumbled a bit when heading towards the door with his school bag, Isshin drew the line. His son wasn't going to get anything done in class, anyway, from the looks of it. He intercepted Ichigo before he could get to his shoes, skidding to a halt with his usual goofy grin but refraining from attacking. "Ichigo!"

Tired brown eyes blinked at him.

Isshin's—this time mostly faked—flamboyant cheer evaporated. "Go back to bed. You're not going to school today; I'll be up to check on you later."

Ichigo blinked again, clearly taken aback by the shift in attitude, but didn't protest.

That was very… _telling_. Isshin's worry grew sharper as he watched his son drop his school bag on a kitchen chair before stumbling his way back up the stairs.

_xxxx_

"Uwaaa!" Tatsuki stared into the Kurosaki dining room through what once was the wall, gaping in shock. When the teacher hadn't bothered to roll-call Ichigo, only muttering 'Right. Parental call in,' when she got to his name and Tatsuki had been worried for her best male friend.

Kurosaki Isshin wasn't known for 'calling in' except once a year, and Tatsuki knew the reason behind that once a year. Considering the man was a doctor with his own clinic—a sniffle wasn't going to have Ichigo getting a free pass out of school.

Thinking of Isshin, he was talking to someone on the phone about repairs and the clinic had the 'closed' sign up. The man sighed audibly as he hung up the phone before turning to face the hole in the side of his house and wave tiredly, "Hello, Tatsuki-chan."

Now Tatsuki was _more_ worried. The crazy idiot was usually a lot more… _dramatic._ "Isshin-san? What happened?"

Isshin was silently grateful they'd agreed on a cover story. "A delivery truck ran through the wall last night; Ichigo and the girls were in the room. Of course, when Ichigo noticed it through the window he got the twins out of the way and _they're_ fine, but…"

Tatsuki's blood ran cold, "Is he…?"

"He's sleeping," Isshin sighed, rubbing a hand over his face wearily. "He was only a bit bruised by the impact itself, but one of the snapped wires shocked him pretty bad. I thought—I thought I'd lost him for a while there. His heart stopped for almost three minutes."

Tatsuki swallowed and Isshin came closer to the missing wall, reaching to give her a hand up to the dining room. "Has he… is he… all right?" Brain damage was a very real possibility.

"He was lucid earlier; stumbled his way downstairs to ask after Yuzu and Karin as soon as he woke up, and then he had the nerve to ask if _I'd_ been hurt, so no blatant personality changes or obvious memory loss. I've got an IV and a heart monitor hooked up to him just in case," Isshin gestured to the beeper attached to his waist. "Right now, though, the best thing for him is rest."

Tatsuki nodded shakily. At least now she knew why Isshin wasn't as crazy as usual. "Can I see him?"

"Not today," Isshin shook his head. "He needs the sleep and I don't dare give any hypnotics or even sedatives* under the circumstances. He'd wake up if you went in. If you come by tomorrow after school, you can see him then."

True enough. Ichigo was pretty light sleeper, no thanks to his father's usual wake-up calls. "Ichigo's friend Sado…"

"Bring him along. I don't have his number; could you let him know what's going on? It'd be easier to get all this," a vague gesture indicated the mess that used to be a wall, "sorted without him coming by."

"Sure," Tatsuki made as if to go towards the front door and Isshin offered a wry grin.

"Might as well use the temporary entrance while it lasts."

Tatsuki chuckled halfheartedly and turned to hop down out of the broken wall. "… Take care, Isshin-san."

_xxxx_

Isshin sighed as Ichigo's black-belt friend left. Aside from the part about trucks and electricity, everything he'd said was true. Ichigo hadn't even protested the medical equipment too much.

What he _hadn't_ said was that Ichigo had started running a fever a few hours before. The IV had a dose of fever reducers, but Ichigo's exhaustion hadn't been helped by his taxed immune system giving in to what was shaping up to be a bad cold. Not deadly even under the circumstances, so long as Ichigo kept hydrated, but he was going to be in for a miserable few days.

"Tadaima*!" Yuzu's voice echoed from the front door and Isshin blinked.

"What she said," Karin kicked off her shoes much less neatly than her sister, but she did pick them up and put them out of the way.

They'd walked right past the open wall and Isshin had been so absorbed in his own thoughts that he hadn't noticed. He'd have to work on awareness again. Just because he couldn't currently see spirits, didn't mean there weren't ways of telling they were there—and he'd _really_ rather know when someone was in his house.

"Oi, Oyaji, how's Ichi-nii?"

… and there came the question he didn't really want to answer. Even though he _knew_ that Ichigo should be fine in a day or two, Isshin couldn't quite manage to stamp out his own fears. The girls were going to be _so much worse._

When Ichigo started feeling better, he was going to kill Isshin for worrying his sisters.

_xxxx_

Ichigo blinked, slow and hazy. His room was dark and he remembered… _not_ going to school in the morning. He'd slept the entire day? No wonder he felt groggy.

He blinked again, using the faint moonlight to confirm he was in his own room—and… huh. _IV and_ _heart monitor?_ The monitor was silenced and had the little green 'transmitting' light on, which meant the information was being sent directly to a hand-held alarm. Which meant… Jeez, he'd been _way_ more out of it than he'd thought.

What had happened? Had he been asleep for more than a day?

"Ichigo?" Query. Quiet but firm.

"… Oyaji?" Ouch. That was kind of… stinging, really, with a dry throat.

"You have a fever," Isshin looked him over for a moment and moved closer to help him sit, passing over a glass of water from the desk. "It's gone down quite a bit, now. You'll probably be able to head back to school the day after tomorrow."

Ichigo accepted the water gratefully, sipping to sooth the dryness in his throat. "How long?"

"A little over twelve hours. Your immune system took quite a beating last night; it's no surprise that you got sick."

"Hm," Ichigo passed back the empty glass and Isshin stepped back.

"Try to stay awake for a bit longer. Yuzu made chicken-and-rice soup earlier and we saved you some. I'll go heat it up."

Ichigo watched silently as his dad left the room with the empty glass, everything feeling kind of surreal. Isshin was acting like a responsible adult?

The world was doomed. He was going to wake up in the morning to find fire and brimstone raining from the sky.

_xxxx_

_Sedatives: a class of medication used for calming a patient via chemical. Despite common misconception and side effect, sedatives are not designed to be sleep aids. Medications intended to cause sleep or unconsciousness are hypnotics._


	4. Chapter 3

_**Chapter 3**_

_Or: The Chapter in Which Not Much Actually Happens_

"Oh, Ichigo!" Rukia blinked at him when he settled at the breakfast table next to Karin, who smiled faintly at her brother's presence.

"Feeling better, Ichi-nii?"

"Yeah," Ichigo gave his little sister a smile before casting a glance at the hasty patch-job that had been thrown over the hole in the wall. "I don't know how I slept through _that_, though."

"I put up a barrier around your room," Rukia explained. "It's supposed to keep people from getting through from the outside, but I modified it to block sound so you could sleep."

"Huh," he eyed the Shinigami appraisingly, "You guys can do things like that?"

"Only if we're good with Kido," Rukia stated. "Nii-sama threatened to get tutors from the Kido-Corps to teach me if I wasn't up to his standards with any commonly used spell under thirty-five. I made sure to study _very_ hard."

"How many spells are there?" Yuzu asked curiously as she set a plate of rice and eggs in front of her brother, giving him a bright smile. "And I'm glad you're feeling better, Onii-chan."

"The standard Kido spells are numbered one through ninety-nine, ranked from weakest to most powerful. There are that many of each Bakudo and Hado spells. I don't have enough reiatsu to use anything over thirty-five easily, though, and I can't cast over sixty-five at full strength without wearing myself out."

"So… Bakudo are restraining and Hado are offensive?"

"Right," Rukia nodded, pausing to let Yuzu set a plate in front of her, "Arigato, Yuzu. Bakudo are for either restraining or defense. Hado are damage-causing, mostly. Even Hado #1, 'Sho' can cause damage if you give it enough power, although it usually just knocks someone back. However, very few Hado are actually used commonly. Most Kido-users have certain favorites that they use often, and the others are left mostly unused except when learning."

"Oh?" Ichigo glanced at her, chopsticks pausing on the way to his rice.

"Aa, for instance, I usually use Hado thirty-one, 'Shakkahō.' Nii-sama favors number four, 'Byakurai'… but Nii-sama has always preferred precision, and he has the reiatsu to make it pierce through most things easily. Even most Lieutenants can only cause electric burns with Byakurai, and lower-level practitioners just give mild shocks."

Ichigo blinked at that, "By the way, who's your brother?"

"Kuchiki Byakuya, Captain of the Sixth Division."

"So…" Karin considered the conversation so far, "I get that 'Byakurai' is some kind of electric spell and Shakkahō is a fire spell, but aside from that, what's the difference?"

"Byakurai produces a lightning-like bolt of electricity, though usually not very powerful. Shakkahō makes a fiery red orb that causes a small explosion where it strikes. Shakkahō is a more powerful spell in general and tends to be easier to aim. Also, even if it misses, the shock wave from the explosion can sometimes knock an opponent off-balance, whereas Byakurai only tends to leave scorch marks on what it hits if you miss your target."

"So you prefer using something that can help you out even if your opponent dodges, huh? Makes sense to me," Ichigo shrugged, "Meanwhile; Karin, Yuzu, you should hurry. You don't want to be late."

"The old goat isn't letting you go to school today, is he?" Karin half-asked.

Ichigo scowled, "Idiot's lost his mind. He's being… _overprotective._ Him!"

"I know," Karin twisted to peer over the stove at the kitchen window, the usual dining room window missing and the wall boarded over in a hasty patch. "Is the sky falling? Usually he's the one trying to beat you up."

Something beeped.

"Oh?" Rukia blinked, pulling her not-a-cellphone out of her pocket. "Moshi-moshi?"

A pause, "Oh! Ukitake-taicho! Hai, of course."

She clicked the phone shut and turned her attention to Ichigo, "Taicho is coming today—he was just given leave by the Soutaicho. Isane-fukutaicho will accompany him."

"Isane?"

"The Lieutenant of the Fourth Division. Unohana-taicho is required at the Fourth today—something about a Kido accident involving Eleventh Division. I'm pretty sure I don't want to know. Anyway, I need to go on patrol—I'll leave my Gigai with Chappy."

"… Chappy?"

A rabbit-shaped Pez-dispenser-ripoff was the response. An instant later, Rukia and a mobile Gigai were two separate entities and the mobile Gigai was _visibly_ cheerful. "Chappy, listen to Ichigo and his family if they tell you to do something and stay out of trouble."

"Understood!"

Ichigo and Karin edged a bit away from the exuberant declaration, Karin wondering what had just happened.

"Bye, Rukia," Ichigo waved as the Shinigami opened the front door to leave.

"Later," Rukia closed the door behind herself.

"What just… happened?" Karin asked, suddenly wishing she could see Shinigami and not just normal spirits. Which was ridiculous, as she steadfastly refused to admit the spirits she _could_ see were real. But then… normal spirits didn't effect the world around them, did they?

"Rukia went out on patrol, apparently, and left Chappy in her fake body. I think she called them Gikongan. Kind of like pre-programmed soul replacements that are supposed to keep a Gigai running without a Shinigami in it, but not advanced enough to really be self-aware."

"Huh," Karin eyed the smiling Chappy, "Well, all right, then. Yuzu! Let's get going."

"Right! I'm ready! Here's your bag, Karin."

Karin nodded at her twin as they moved to the door, "Thanks, Yuzu. Later, Ichi-nii."

"Bye, Onii-chan!"

"Bye Yuzu, Karin. See you after soccer* practice."

_xxxx_

Knowing there would be company fairly shortly, Ichigo settled onto the couch with his schoolbooks instead of heading back to his room.

Isshin appeared in a flurry of movement, "Ah! I missed seeing my daughters off to school!"

Ichigo groaned, "Well, you're closer to normal today. Ukitake-san and the Lieutenant of the Fourth are coming over soon. You going to be all right? And… what's with you? You feel all… _weird._"

"Oh, you noticed that? My friend Kisuke made me this!" Isshin proudly displayed a wide, somewhat fuzzy wrist-band. "It makes other people feel my reiatsu as a sort of inverted version of my normal signature!"

Ichigo rubbed his temples, "At least now it matches your usual attitude."

"Exactly!"

"That wasn't a compliment, you lunatic."

"… _Anyway_," Isshin scowled, though he didn't look particularly offended, "I'm going to go get things set up in the clinic. We're not taking walk-ins until the wall is fixed and we don't have any regulars scheduled until the end of the week, so we're officially closed until then. It'll make it easier to deal with Shinigami that way."

"Yeah, yeah. I'm trying to finish the bookwork from yesterday that I missed before they get here. Tatsuki sent me the page numbers."

Isshin waltzed towards the clinic, waving dismissively, "Don't work too hard!"

Ichigo huffed, returning his attention to his notebook and jotting down the next answer. "Idiot."

_xxxx_

"Come on in," Ichigo stepped aside, intrigued by the casual modern clothes Ukitake-san wore. The look wasn't _bad,_ per say, but it was clear the Shinigami Captain was uncomfortable in jeans and a long-sleeved polo.

He smiled anyway, stepping through the door to make room for the woman who'd come with him, "Ohayo, Kurosaki-kun. This is Kotetsu Isane, Lieutenant of the Fourth Division. Isane-san, Kurosaki Ichigo. He's Shinketsu."

Ichigo took a moment to examine her as he returned the greeting. She was wearing a casual unpatterned kimono of a deep blue and her hair was a steel-grey with a unusual style.

He was starting to get the feeling that Shinigami didn't exactly adhere to human hairstyles from _any_ era.

"Shinketsu? How unexpected. Good morning, Kurosaki-san."

"Oyaji's in the clinic; he'll turn up sooner or later. Meanwhile, do you have the blood sample from your normal form, Ukitake-san?" Considering how long the Captain had been suffering from the disease, the bacteria would show up in his blood, which made things a bit easier.

"Oh, I have that," Isane reached into a small purse tied to her obi, producing a modern-style test-tube with the requested sample. She handed it to Ichigo, "What do you need it for?"

"Oyaji's going to need some samples from the Gigai to see if the bacteria transferred over properly, but he won't be able to see this one. First I need to set up a microscope and take a look at it—Oyaji already got his hands on some Rifampin—if this is Tuberculosis, there's no reason it would be antibiotic resistant, so Rifampin should work fine in theory. But… well, spiritual entities can only really be treated by something made of spirit-particles, right? I need to see if I can flood enough reiyōku into the antibiotic to get it to work the way we need it to, but it's better to test the results on a blood sample than a person. You can see if it works a lot faster."

"Interesting," Ukitake murmured, privately thinking it sounded a bit more like one of the Twelfth's experiments than the Fourth's treatments. Things were _very_ different in the Living World.

"Do you mind if I watch?" Isane asked.

Ichigo shrugged, "Go ahead. You might even be able to help; I have _no_ experience in deliberately saturating something with reiyōku. I mean, pretty much the entire house got that way when I was younger, but that's because I didn't know how to hold it quiet until I was almost ten."

Ukitake and Isane both stopped to stare. That… implicated something frightening.

"Your power feels to be at about the level of my own from here, but I couldn't feel you at all from the street," Isane stated, slow and careful.

"Your own…? Your reiatsu does feel kind of restrained, so I could see that. Anyway, this is as low as it goes. I can keep it… _contained,_ I guess. Held in a small area. It got the Hollows to start ignoring me when I didn't have a way to use my power."

"And how _did_ you bring out your power? I know the Hollow forced you from your body, but…"

"Before that, Rukia had been thrown into that light across the street—the one that's all dented now. She was pretty dazed. I went to help her… I think I touched her sword. Something—_woke_—just before the Hollow hit me. I didn't even realize I'd left my body at first, just that I had a sword and therefore a way to _fight._"

"I bet the Hollow wasn't expecting _that,_" Isane smiled a bit, considering the explanation. It actually made sense, considering that Shinketsu were _born_ Shinigami. A Zanpakuto would already be with even a human-born Shinketsu; once released from the body… well. The result was fairly predictable. "Well, it's not unexpected, at any rate. Your Zanpakuto would have been with you either way, but to have it _awake_—even without Shikai, that would help."

"Would you be willing to leave your body and show us your Zanpakuto?" Ukitake asked.

Ichigo shook his head, "Oyaji said that my heart stopped while I was out. That's… _really_ hard on a human body, even for only a few seconds." He held up a hand in demonstration, a fine tremor still shaking though his fingers. "Longer than three minutes… well. The damage tends to be irreversible, at least with human methods. I'm sure Unohana-san did her best, but I was apparently delirious with fever most of yesterday, and Oyaji's still freaked enough to keep me out of school today. You guys… don't really have a way to help physical forms ward off infection. Healing Kido may even have made it _worse,_ strengthening the bacteria while my immune system was down."

Isane blanched, eyes skittering to Ukitake. "Healing Kido… made it _worse?_"

"Probably, yeah. I mean, your healing Kido reinforces the bodies in comes in contact with, as well as healing damage, right?"

"That's correct," Ukitake replied after Isane seemed unable to.

"Well, viruses and bacteria would both take advantage of that. In your case, it wouldn't be that bad, Ukitake-san. With actual damage and an uncompromised immune system, you'd be strengthened enough that the bacteria in your system wouldn't get any real advantage from it. In my case, though…" He shrugged.

"When the heart stops, a human's immune system becomes unable to function. Unlike the heart, however, getting the immune system working again takes time. Which means I had no real way of fighting off infection; and to add to that… what I've got right now is a virus, not a bacteria. We don't have any viable anti-viral medications that don't have some pretty nasty side-effects. Oyaji pumped me full of fever reducers yesterday so I wouldn't die, but I'm still pretty beat."

"That… could be a problem," Ukitake stated faintly, "I did not realize you could come to harm from simply leaving your body… You need training to be able to properly defend yourself, but if you can't leave your body you will be restricted to Kido, and with the amount of reiatsu you have access to, Kido will be difficult for you to learn. It is much easier to learn Kido before you have grown into your power, when you have less reiatsu available to you and can control it more easily."

Ichigo led the way to the living room and the trio settled around the table, "Rukia left a... Gikongan, I think she called it, in her Gigai before she went out on patrol. I don't know if one of the ones you already have would work properly for a human body, but anything that keeps basic vitals going should keep my body healthy enough. That said, I'd like to learn Kido anyway."

"Oh?"

Ichigo shrugged, "Well, how long does it usually take for a Shinigami-in-training to be able to access their full power?"

"The normal Shino-rei Academy curriculum is eight years, and most graduates take at least ten more before they get even halfway to their full potential," Isane stated. "So… to reach full potential? Anywhere between forty years to a few centuries, once they start training."

"Well, I've always been able to see spirits, even Hollows and Shinigami. When I was younger, I didn't know how to tell normal spirits and Shinigami from living humans. Hollows… teachers would tell me I had a 'vivid imagination' to come up with monsters like that. Kaa-san told me not to talk about them to anyone and to run if I saw one. When it comes down to it, though… I've never really tried to use my power. Only hold it quiet."

"That is… mildly terrifying," Ukitake admitted. "You've already stated that this is as low as you can hold it, and now you admit it to be _completely_ untrained? That means this is likely only a fraction of your true power, because most of it would be locked deep inside your soul until you learn to call it out."

Isane wavered a bit, "Actually, Ukitake-taicho, you may be viewing that a bit narrowly. Shinketsu or not, Kurosaki-san is still a _living_ soul."

A pause.

"Ah. Of course. That is… quite… well."

"What does that have to do with anything?" Ichigo asked, suddenly wary.

"Simply put, Kurosaki-san," Isane sat back, placing her hands before her on the table, "living souls are capable of growth that the souls of the dead are not. Something about being connected to a living body enables a soul to change. In the case of ordinary humans, this usually means little. Without the physical resilience to survive great damage, most humans do not live long enough to gain much power. The few that _do_ gain power before death usually are unable to access it until after. However, some have enough power and knowledge of that power to use it. Those that do… unlike normal Shinigami, who only gain greater access to latent power hidden within the soul, living souls do not necessarily—or even primarily—learn to access hidden power," the lieutenant gave Ichigo a level stare.

"Instead, living souls begin to produce _more_ power. As long as you are alive, it is unlikely that you will learn access power in the same way ordinary Shinigami do. If you find yourself in need of more power, it is likely that the power you already have access to will grow… which means the power of yours which is hidden will grow as well."

"Huh," Ichigo considered that.

"Kurosaki-kun," Ukitake said slowly, "I am going to place a barrier around this room. After I do, please stop hiding your reiatsu; I would like to know what I will be working with when beginning your Kido instruction."

Isane was probably the least powerful Lieutenant, truth be told. She was skilled, _especially_ in healing, but her reiatsu ranked at about a five, which was closer to the level of the average fourth or third-seat than the average lieutenant. Still, fourth-seat level without training and while suppressed?

The nod from the teen was enough to have him place a silent barrier. If one was skilled enough, one could cast without incantation. Incantations required _breathing_, so Ukitake had learned not only to cast without incantation—which usually reduced a spell to between a fourth and a third of full-incantation power—but to _incant_ _silently_. He hadn't made that common knowledge.

"Ready, Kurosaki-san."

The boy let out a breath and closed his eyes, releasing the hold he had on his power.

Silent thundering concussive _force._ The couch at the boy's back slid and toppled until hit the barrier and Isane gave a startled 'oof' as the table hit her in the gut, only the fact that she'd been shoved back as well keeping her from what would have been a bad bruise.

Ukitake's eyes widened as the reiatsu settled, the brief glow and shove of 'higher-than-his-own-Shikai' power settling to something around 'Byakuya on a bad day'. At least an eight, possibly a nine.

Captain class. _Untrained._

"Well," Ukitake cleared his throat, "I can see how that could draw attention. And possibly have normal humans collapsing unconscious."

Ichigo frowned and stood, reigning his power back in as he turned to right the couch so it wouldn't fall when Ukitake released the barrier. Considering what he'd just been told about living souls growing under duress—if his power was enough to knock humans out, he'd probably have ended up spurring anyone he spent any significant time near into developing their own power. And from what his father had said, _that_ would attract Hollows.

Yeah… he was going to work on figuring out how to restrain it _better_. Anyone who spend a lot of time within five feet of him might gain power anyway. Tatsuki and Chad… maybe even Keigo, the _way_ too touchy idiot.

"Since you have so much reiatsu, I'm going to try teaching you some higher-level Bakudo first. They require more power than same-level Hado, are significantly less _damaging_, and if you don't have to worry about restraining your power as well as shaping the spells, you will be able to break down learning Kido into steps. In fact, so long as we don't start with any of the wide-area spells, it would even be possible to practice indoors."

"Cool," Ichigo tugged the table back into its usual spot and pulled his power back in again, giving Isane a worried look as she hadn't said a word since getting hit by said table. "Oi, are you all right?"

"Oh… yes," Isane straightened, her hand lighting a pale green. "Just a little bruising—there."

"Yeah, sorry. I wasn't expecting that to happen," Ichigo rubbed the back of his head sheepishly.

"I'm surprised you could repress it so much," Isane admitted. "It's very difficult to lower your reiatsu by more than a fifth without limiter seals. It feels like you managed to lower it by over _half_… and then there's whatever you're doing to keep your reiatsu from reaching past about five feet…"

"You can't do that?" Ichigo was honestly surprised. "But—it's your own power. Why wouldn't you be able to direct how far it goes?"

"It doesn't usually… work that way," Isane stated delicately, although it made a strange kind of sense… if you tossed out generally accepted knowledge about spiritual power and the way it worked.

Ukitake coughed lightly, "Normally, reiatsu puts pressure on everything it comes in contact with. Because of that, it is much like tossing a pebble into a pond—the ripples spread out whether you will them or not. What you are doing is like restraining a ripple, or perhaps preventing a ripple from forming. I have not heard of anything quite like it—it's certainly possible to hide one's reiatsu by holding it completely within the body, but once it reaches past your skin, it should be easily traceable by anything within range. What you are doing is—very strange."

"I tried holding it entirely within my body at first," Ichigo admitted, considering the implications, "but I ended up with a really high fever. So then I tried limiting the area—it took a while to figure out how, but it works."

It _shouldn't._ Spiritual pressure didn't work that way.

Ukitake Juushiro was starting to get the feeling that 'impossible' wasn't going to mean much with Kurosaki Ichigo around.

_xxxx_

Isshin huffed at himself. Juushiro was in the house, and he knew that the man would remember him. However, if he played dumb… well, his reiatsu would feel so different from what it really was that it should be possible to convince the man that he was—well, _not_ Shiba Isshin.

Which… he wasn't, not anymore, not really. It hadn't been long, by Shinigami standards—not even half a century—but too much had happened for him to be that man anymore. He'd begun living at a human pace, the rhythm of life so much _faster_ than it had ever been in Soul Society.

Ultimately, he'd be found out. There was no way to avoid it forever, not with his son being in direct contact with the Gotei already. For now, though… well, for now he could keep his head down. After a fashion, anyway.

Shiba Isshin, Captain of the Tenth, hadn't been nearly as flamboyantly insane as Kurosaki Isshin. The former Shinigami grinned to himself—_that_, he could work with.


	5. Chapter 4

_So, I finally got myself some time and typed up the next chapter. For that matter, I also watched the Xcution arc of the Bleach anime._

_So, does anyone else see Kuchiki Byakuya's declaration of "I do indeed owe you a great debt and you have my gratitude. However, you are Kurosaki Ichigo's enemy. Therefore, no matter how much I owe you, I will kill you without a moment's hesitation." declaration to the memory-hijacker the next best thing to a claim of complete and total devotion? (What _kind_ of devotion may be up to debate, granted, but from Byakuya it's quite the statement.)_

**_Chapter 4_**

Ichigo glanced over at the clock, wondering what was keeping his father. "Maybe I should check on Dad," he stood up, moving to open the door separating the house and clinic.

The flying kick was unexpected but easily countered. "Dammit, Oyaji! What have I told you about attacking me whenever I open a door!"

Isshin gave a weak thumbs-up from his new position upside-down in the corner, "Nice counter, son!"

Ichigo sighed, running a hand through his hair. "Well, at least _you're_ back to normal."

"Isshin!?"

"Oh?" Isshin rolled himself to his feet, looking at the Shinigami Captain who was staring at him. "My son! You haven't introduced us properly!" He turned on Ichigo with an out-flung fist.

Ichigo leaned out of the way, braced a hand against the wall, and kicked Isshin's feet out from under him. "Idiot! Will you stop acting like a tantruming three-year-old for _five minutes?_"

"Why is he acting like this is normal?" Isane asked Ukitake warily.

Ichigo snorted and turned his attention back to his guests, "Ignore his antics," he gestured towards the pouting man-child behind him, "Anyway, Ukitake-san, Isane-san, this is my dad; Kurosaki Isshin."

Ukitake stiffened slightly—name _and_ face couldn't be coincidence, but the former Tenth Captain had gone missing years before… labeled KIA during a living-world mission where his reiatsu had spiked dramatically before disappearing from the Twelfth's scanners. _Something_ had happened.

"Oyaji, Ukitake Juushiro and Kotetsu Isane. _Try_ to behave while they're here."

Ukitake examined the man surreptitiously. Isshin wasn't showing any signs of recognition and the fact that he had no more reiatsu than a normal human was worrying enough, but it was worse that what little power he possessed felt nothing like the Shiba's _should_ have. If he truly had no memory of whatever had caused it… they might never know what had happened to him.

But at least it gave an explanation for inborn Shinigami abilities. The Shibas _were_ a true-blood family, and regardless of present ability, Isshin's blood remained what it was. And if he had married a spiritually aware human… well, it explained the insane reiatsu levels of the Shinketsu-human teen… and his facial structure, so similar to Kaien.

But if Isshin didn't know... the man had a human life—if a brief one—and a family. And apparent insanity that went far beyond even Shiba norm. Should they tell him? Try and get him healed?

A hand on his forehead broke Juushiro out of his thoughts.

"Oi, Ukitake-san, are you all right?"

"Oh… aa, I just got distracted," the Thirteenth Captain smiled at the younger Kurosaki.

Ichigo scowled slightly. He could only guess at what was going through the Captain's head, but knew better than to push the line of questioning, "If you say so. Oyaji! You got your kit? Let's get this thing started!"

_xxxx_

(Many) hours later, diagnosis confirmed and tests with reiyōku-saturated Rifampin against bacteria in the blood samples having shown very positive results, Ukitake was given his first dose of medication.

"We should start seeing sure improvement within a few weeks," Isshin informed his friend, regretting that he couldn't show how well he knew the Shinigami Taicho. "There's no way to say exactly when, as you're not… well, _human_, but even after you start feeling better, you need to take the medication as instructed. If we don't run you through the full regimen, we can't be sure that the illness won't return—_especially_ if you've had it as long as you say you have. And… this might be a bit inconvenient, but it would be best if you remained in the… gigai?" Isshin waited for the slight nod of confirmation on the term, "For at least the first two weeks. It would be best to remain in it for the entire treatment session, but I'm guessing that might not be possible since you said you're one of the leaders. For now, though, you can take one of the clinic rooms so we can keep an eye out for any unusual reactions. As for you, Kotetsu-san, you said you're one of his doctors?"

"Healers, but yes."

Isshin nodded, "I'll write up a list of things to watch out for and instructions on the medication's use for you. Again, I'd prefer he remain in that… gigai… for as long as possible during the treatment."

Ichigo nodded at that, "Lets get you settled in, Ukitake-san. This way."

Ukitake himself was still too overwhelmed to come up with actual words and followed Ichigo in a half-daze, not quite able to wrap his mind around the unexpected cure. He hadn't allowed himself to truly hope this spur-of-the-moment idea a human teen had tossed at them would actually _work_, but Isshin, Isane, and Ichigo _all_ declared it to have a very good chance at being a cure.

Hope, he discovered, was a stunningly sharp thing, cutting as deep as grief with an edge made of possibility instead of loss.

_xxxx_

Isane stayed for another two days before being recalled, but Ukitake had been put on medical leave by the Healer-Captain and continued to stay at the clinic. Ichigo sighed; with only one person who had known his father while the man had still been part of the Gotei, it was a little easier to keep the fact that Isshin remembered a secret.

Isane-san had figured out who he was on the second day, and Ichigo was fairly certain that the Thirteenth Captain had figured it out in the first twenty seconds. He hadn't said anything, though, and there was a recurring gleam of worry when the man glanced at Goat-Chin.

Well, hell with it—it was a gamble that he'd mentioned to his father late the night before, just to make sure he had approval—time to confront Ukitake.

If he did it right, the belief that Isshin was oblivious would be reinforced and Ichigo could freely admit to knowing his father had been part of the Squads. Captain of the Tenth… well, it helped explain his own power, at any rate.

Ukitake had headed over to a nearby park—no real surprise that he liked it there, as most of Karakura was steel and concrete and the parks held the majority of the larger plant-life in the city—so Ichigo headed out.

"Oi, Ukitake-san," he called once he was within easy range, "Can I talk to you?"

The Shinigami turned, smiling, "Of course, Ichigo-kun," he paused, taking in the teen's expression. "Is something wrong?"

Ichigo shook his head, "Not… _wrong,_ no. It's just—you keep looking at my Dad like… like he's been hurt and you can't help. Like you _know_ him, and are sad for it."

Juushiro stared for a long moment, then shook his head with a soft sigh, "You are very perceptive, Ichigo-kun. I believe I may have known your father some time ago, yes, but I do not have any real knowledge of his history and cannot be completely certain."

Ichigo shrugged, "All I know is that Mom found Dad half-dead and took the time to see him healthy again. He fell in love with her, eventually they got married. He said his first memory of this life was looking at the face of his angel." Not—quite—true. Oh, his dad _had_ said that, exactly that, with emphasis on 'this', but he had more-or-less made up the rest of it. He'd tell his father what he'd said when he got home.

If he'd tried to deny and anyone had bothered to look at records, there was no telling what could happen; this way it was a combination of confirming suspicions and insuring Isshin's current separation from Soul Society. Powerless and without memory? They had no real reason to try and bring him back, and he got the feeling that this man, at least, was willing to stand up for his old friend.

"So… he _is_ Shiba Isshin…"

"I don't know," Ichigo shrugged, "He took Mom's name when they married."

"He's all but powerless, and what little power he has feels… _broken_. His Ribbon is white; he is without his Zanpakuto, and… well, with that in mind, perhaps it's better that he doesn't remember. I don't know what I'd do if my blade's soul was torn from me."

Ichigo understood, sort-of. He could feel his own blade, for all that he had yet to speak with… him (probably a 'him', anyway). Even with a bond so tenuous, he was certain it would be _agony_ to lose that presence in his soul.

Which actually could explain quite a bit of Isshin's insanity. Forceful distraction from loss—the man had gotten even more erratic after Masaki had died.

Ichigo sighed again, "Yeah, I think I know what you're saying. I can only feel mine, and already I think I'd… well. If _I _feel this way, I don't know what it would be like for someone who could _hear_ their blade."

Ukitake remained silent for a long moment, then shook his head and changed the subject, "Well, since we're both here and it's a lovely afternoon… is there somewhere nearby where we could get in a Kido lesson?"

Ichigo nodded, a hint of a smile passing over his face. "Yeah, there's an abandoned construction site not too far. This way."

_xxxx_

Ichigo considered the rectangular shield in front of him, broader and taller than his own frame by perhaps two feet in each direction, as evidenced by the sudden three-inch thick imprint in the dirt. It was transparent, almost invisible—and had been _much_ easier to cast than he'd expected.

"Huh," he said.

Ukitake blinked. "Well. I didn't expect you to get it up at all on your first try. Maintain that and I'll throw a few lower-level Hado at it. If it doesn't hold, duck."

'Sho' washed off in a puff of displaced air and the captain worked his way up by skipping three spell ranks each time. He got to 'Shakhakko' before stopping. "It seems solid and while it also seems like it could take much stronger spells, it would be dangerous to test that while you're in your human body. Go ahead and let it dissipate."

Ichigo nodded and a the pane of energy shimmered out of existence.

"How do you feel?"

Ichigo considered, then shrugged, breathing deep and steady. "Like I've jogged a while? Not bad, but a little out-of-breath and a little energized, I guess."

"Well done," Ukitake smiled, "Danku, working on the first try. I'm impressed."

"It wanted enough power that it was easy to shape," Ichigo explained. "That's what you planned on, right?"

"Yes," the man's smile widened, "Still, I expected it to take a few tries before you got it right… but, then, you've been manipulating your power outside your body for a while now, haven't you?"

Ichigo thought that over, "Yeah, I guess. It doesn't feel the same, though. This kido is much easier. It doesn't fight me; it pretty much shaped itself. The words actually do something, don't they?"

Ukitake nodded, "Danku is simplest of the high-level Bakudo, the only one that doesn't need an actual incantation. There is one, of course, but it focuses just as well without it, so no one actually bothers to remember what the incantation _is_. All the focus for the spell snaps into place just by saying 'Danku'. Do you think you could create it without the name? It usually weakens a spell by at least sixty percent, but I'm not sure how you shape reiyōku, so you might be fine."

Ichigo shrugged and brought up the pane-like shield again, silently pushing his power into the same pattern it had snapped to when he'd spoken the spell. A little harder, but…

Ukitake frowned, inspecting the result. "Perhaps a _bit_ less stable, but certainly not by any great amount. What were you thinking about when you made it?" Had Ichigo incanted silently, as he had learned to?

"I just pushed it into the pattern the name had pulled it into. It's not quite right along the outer edge, but I can fix that with some practice. The middle of the pattern is octagonal—not all that stable. I think if I just…" he reached out with _something_, formless as thought, and tugged at the power in the shield, turning the octagon into connected triangles, threads of power that would shunt impacting force outwards, to slough off the edge of the shield instead of concentrating the force at the middle. The edges… hmm…

A mild curve, ragged? Better in case of nearby innocents or allies, starting out jagged and tapering into almost-thread to catch and disperse force.

Ukitake gaped, "What did you just _do?_"

"Hit it with something heavier than that red fireball," Ichigo instructed, holding the shield in place as he stepped around to the front of it, beside the now even more baffled Captain.

Said Captain was clearly repressing the urge to stare at him, but nodded. "Sprinkled on the bones of the beast! Sharp tower, red crystal, steel ring. Move and become the wind, stop and become the calm. The sound of warring spears fills the empty castle! Hadou Number 63: Raikouhou!"

Ichigo watched clinically as the wave of yellow electricity impacted his shield—which did exactly as he'd wanted it to. The power was shunted to the edges, tangled briefly in the threads, and dispersed into a shower of sparks. He had a vague thought of a reversed elliptical-type set up, to reflect back, but that would only work if something hit dead-center. Not worth the effort.

Ukitake shook his head slightly, trying to focus. "What did you _do?_"

"I shifted the pattern," Ichigo explained. "The pane with a central octagon was less stable and relied on raw power to endure. I changed it to interconnected triangles and altered the shape to shift force outwards, but that could hurt nearby allies, so I made the edges pretty ragged to catch and diffuse the energy. Hang on, though—Danku."

The word pulled his power into the first pattern.

"Huh. So, I don't have an incantation for that. I'm pretty sure it'll take at least thirty seconds to get up, too… I need to practice."

Ukitake shook his head again, smiling wryly. "Well, now that you have made an entirely new kido that has neither name nor incantation, shall we try a lower-level Bakudo? I would like to see when it becomes difficult for your power to form the spells."

_xxxx_

Ichigo rolled his shoulders, a little tired but pleased. He hadn't been able to control anything under seventy-three and Tozansho itself was unstable, but now he had something to work on. Ukitake, however, was starting to look pretty worn out. "Oi, Ukitake… let's head back, huh? You're getting better, but you've still got a while before you're illness will be gone. Don't push too much."

"I'm fine," the Captain assured.

"No, you're not," Ichigo snorted, "You've gotten used to it, I'm sure, but if you push too hard, it'll just take longer for you to get well. So get better, _then_ push your limits."

Ukitake bowed his head slightly, smiling. "Aa, well, then… I'll defer to your judgment, Ichigo-sensei*."

_xxxx_

_*Sensei—the closest English translation is probably 'teacher', but there are a myriad of other uses for the honorific that reflect more on how a person is viewed than actual profession. The term is often applied to doctors, especially family doctors. In this case, Ukitake's use falls somewhere between gently mocking and genuinely respectful._


End file.
